System for removing per- and polyfluorinated alkyl substances from contaminated aqueous streams, via chemical aided filtration, and methods of use thereof

ABSTRACT

A system comprising an agitation and flocculation system and a particulate filter capture system, and optionally a feedback system and/or a water softening. The agitation and flocculation system configured to receive a contaminated aqueous stream and an anhydrite quantity, and comprising means for agitating the aqueous stream and a means for mixing the aqueous stream with the anhydrite, such that a precipitate of calcium sulfate hydrate+contaminant complexes is formed. Also, a system comprising a fixed-bed type cross-flow system and a particulate filter capture system, and a corresponding method of removing per- and polyfluorinated alkyl substances from the contaminated aqueous stream. The method comprising the acts of: providing an anhydrite quantity; contacting and agitating the anhydrite quantity with a contaminated aqueous stream; and collecting the precipitate of calcium sulfate hydrate+contaminant complexes formed from the aqueous stream.

BACKGROUND OF THE INVENTION Technical Field

The present invention generally relates to filtration systems. Morespecifically, the present invention generally relates to achemical-aided filtration system for, and method of, removing per- andpolyfluorinated alkyl substances from a contaminated aqueous stream.

The present invention also generally relates to sustainable watermanagement for aqueous streams, water-reserves, and aquifers. These“waters” may be associated with industrial or consumer-goodmanufacturing processes, or the waters may be independent fromindustrial or consumer manufacturing processes (i.e., the waters may benatural but contaminated water-reservoirs or aquifers, or may becontaminated municipal or agricultural water bodies or streams, forexample), all together referred to herein as “aqueous streams”. Thesustainable water management realized by the present invention also mayencompass open water treatments and treatment systems for, but notlimited to, lakes, reservoirs, rivers, ponds, and streams.

The present invention also generally relates to a system for and methodof producing or reducing the inputs, especially harsh inputs, necessaryfor aqueous stream processing. These inputs may be (1) energy, (2) freshwater, or (3) the active ingredients necessary for adequate processing,for example. The present invention also generally relates to reducingthe non-useful, or potentially toxic, outputs from the aqueous streamprocessing. These outputs may be residues laden with unrecovered orunrecycled per- and polyfluorinated alkyl substances that are usuallytoo difficult to capture.

Prior Art

Per- and polyfluorinated alkyl substance (PFAS) contaminated fluidstreams primarily are generated from two main sources: firefighting foamand industrial discharges. For example, for decades, the United States(U.S.) Department of Defense (DoD) contracted for the Military to usefirefighting foam containing PFASs to fight fuel-fires in trainingexercises at bases around the country. U.S. commercial airports alsoused PFAS-containing foam or aqueous-film forming foam (AFFF). AFFF isintended to be directly discharged into the environment, where it isused to fight fires, such as at an airfield training exercise. PFASsalso are found in countless consumer products like non-stick pans (e.g.,pans with TEFLON-like coatings or polytetrafluoroethylene, PTFE orPTFT), food packing, waterproof liners and fabrics, textile coatings andsprays for water, grease, and stain resistance or repellence, inpersonal care products like waterproof mascaras, eyeliners, andsunscreen, in shampoos and shaving creams, and in the associatedindustrial processes for the production of these products.

Consequently, PFASs represent an interesting, growing, increasinglydiverse inventory of chemicals for the general public, scientificresearchers, and regulatory agencies world-wide. Precise knowledge ofthe presence, concentration, interactions, and effects of all PFASs in agiven contaminated unit is difficult if not impossible due to a lack ofconsensus definitions in the field and due to the miniscule scales atwhich PFAS exist. Data-gathering, testing, and environmental monitoringexercises have led to the publication and sharing of various lists ofPFASs, some exceeding several thousand substances in length. Forexample, the U.S. Environmental Protection Agency (EPA) National Centerfor Computational Toxicology has curated a list of PFASs based onenvironmental occurrence (through literature reports and analyticaldetection, for example,) and manufacturing process data, as well aslists of PFAS chemicals procured for testing within EPA researchprograms. The consolidated list contains about 6,330 PFAS ChemicalAbstracts Services (CAS) named substances, with about 5,264 representedwith a defined chemical structure. There is no precisely cleardefinition of what constitutes a PFAS substance, given the inclusion ofpartially fluorinated substances, polymers, and ill-defined reactionproducts; hence, the following serves as a non-limiting representativegrouping of substances spanning and bounded by the below representativelists, defining a practical boundary for the PFAS chemical space at thetime of this disclosure:

https://comptox.epa.gov/dashboard/chemical_lists/EPAPFASRL is a manuallycurated cross-agency research list of mainly straight-chain and branchedPFASs compiled from various internal, literature, and public sources byEPA researchers and program office representatives (note that this listincludes a number of parent, salt and anionic forms of PFAS, the latterbeing the form detected by mass spectroscopic methods), and that thesedifferent forms are assigned unique DTXSIDs, with a unique structure,CAS (if available) and name, but will collapse to a single form in astructural representation observed using high resolution massspectrometry (HRMS) (MS-ready structure representations) or in astructure representation observed usingquantitative-structure-activity-relationship (or QSAR-ready);

https://comptox.epa.gov/dashboard/chemical_lists/EPAPFASINV is a PFASlist of the EPA's ToxCast chemical inventory, and consists of chemicalssuccessfully procured from commercial suppliers (with a small numberprovided by National Toxicology Program partners) and deemed suitablefor testing (i.e., solubilized in DMSO above 5 millimolar and notgaseous or highly reactive), with all or a portion of this inventorybeing made available to EPA researchers and collaborators to be analyzedand tested in various high-throughput screening (HTS) andhigh-throughput toxicity (HTT) assays;

https://comptox.epa.gov/dashboard/chemical_lists/EPAPFAS75S1 list is aPFAS list corresponding to seventy-four (74) unique substances(DTXSID3037709, Potassium perfluorohexanesulfonate duplicated in set,procured from two different suppliers) selected based on aprioritization scheme that considered EPA Agency priorities,exposure/occurrence considerations, availability of animal or in vitrotoxicity data, and ability to procure in non-gaseous form and solubilizesamples in dimethyl sulfoxide; expanded PFAS list of the EPA's ToxCastchemical inventory, and consists of chemicals that are determined to beinsoluble in DMSO above about 5 mM, wherein said chemicals were procuredfrom commercial suppliers (with a small number provided by NationalToxicology Program partners) and were deemed unsuitable for testing dueto limited DMSO solubility;

https://comptox.epa.gov/dashboard/chemical_lists/PFASOECD is a newcomprehensive global database list of PFASs compiled from theOrganization for Economic Co-operation and Development (OECD) listingmore than four-thousand seven-hundred (4700) new PFASs, includingseveral new groups of PFASs that fulfill the common definition of PFASs(i.e., they contain at least one perfluoroalkyl moiety) but have not yetbeen commonly regarded as PFASs;

https://comptox.epa.gov/dashboard/chemical_lists/PFASKEMI is a PFAS listof the KEMI Swedish Chemicals Agency Report 7/15 (provided by StellanFischer), and consists of highly fluorinated substances and alternatives(2015);

https://comptox.epa.gov/dashboard/chemical_lists/PFASTRIER is aninternational community public list of PFASs compiled by a communityeffort including Xenia Trier, David Lunderberg, Graham Peaslee, ZhanyunWang and colleagues, EPA's Dashboard team, the NORMAN Suspect ListExchange in 2015;

https://comptox.epa.gov/dashboard/chemical_lists/EPAPFASCAT is a list ofregistered DSSTox “category substances” representing PFAS categoriescreated using ChemAxon's Markush structure-based query representations,wherein the markush categories can be broad and inclusive of morespecific categories or can represent a unique category not overlappingwith other registered categories, and wherein for each PFAS categoryregistered with a unique DTXSID considered a generalized substance or“parent ID” that can be associated with one or many “child IDs” (i.e.many parent-child mappings) within the full DSSTox database; and

https://comptox.epa.gov/dashboard/chemical_lists/PFASSTRUCT is a list ofall PFAS structures containing a defined substructure of RCF2CFR′R″ (Rcannot be H).

Generally, PFASs, also known as per- and polyfluoroalkyl substances, aresynthetic organofluorine or perfluorinated chemical compounds that havemultiple fluorine atoms attached to an alkyl chain. As such, the averagemember of the group contains at least one perfluoroalkyl moiety,—CnF2n-. A subgroup of PFASs—the fluorosurfactants or fluorinatedsurfactants—are a group of surfactants having a fluorinated “tail” and ahydrophilic “head”. The subgroup includes the perfluorosulfonic acidssuch as the perfluorooctane sulfonate (PFOS) and the perfluorocarboxylicacids such as the perfluorooctanoic acid (PFOA). PFOS and PFOA were themost highly used and most highly distributed PFASs in the U.S untilrecently.

A number of environmental studies have been conducted or are beingconducted into the effects of PFAS contaminated fluid streams. Theconcluded studies tend to indicate that about 95% of the U.S. populationhas PFASs in their body, with further study recommended. The concludedstudies also indicate that PFASs have contaminated tap water for atleast about 16 million people in about 33 states and Puerto Rico, andhas contaminated groundwater in at least about 38 states.

There are no known studies to show that swimming or bathing in watercontaining PFOS or PFOA, for example, can be harmful to human health.Further, PFOS and PFOA are not easily absorbed through the skin, andaccidentally swallowing contaminated water while bathing or swimmingwill not result in a significant exposure. However, due to theirpersistence, possible toxicity, risk of bio-accumulation, and widespreadoccurrence in the bodies of the general population and wildlife atlarge, fluorosurfactant PFASs such as PFOS, PFOA, and perfluorononanoicacid (PFNA) already have caught the attention of regulatory agenciesacross the globe.

There are two dominant attributes of PFASs that make the class ofchemicals especially concerning: 1) PFASs are characterized by acarbon-fluorine (C—F) backbone; and 2) the carbon fluorine bond is oneof the most stable bonds in organic chemistry, giving PFASs a relativelylong environmental half-life. PFASs do not rapidly break down in wateror soil and readily are carried over great distances by wind and watercurrents. Humans are readily exposed to PFASs in the air, in indoordust, food, and water; and in some consumer products. The main source ofhuman exposure to PFASs usually is from eating food and drinking waterthat has been contaminated.

As a result of this concern, the production of certain PFASs areregulated by various governments across the world, or have beenunilaterally phased-out by international manufacturers like 3M, DuPont,Daikin, and Miteni in the US, Japan, and Europe. For example, 3M alreadyhas replaced PFOS and PFOA with short-chain PFASs like perfluorohexanoicacid (PFHxA), perfluorobutanesulfonic acid, and perfluorobutanesulfonate (PFBS). Although short-chain fluorosurfactant PFASs may beless prone to bio-accumulation, concerns remain that short-chain PFASsmay be harmful to both humans and the environment at large.

Several technologies currently are available for remediating PFASs inaqueous streams. These technologies are applicable to drinking-watersupplies, groundwater, industrial wastewater, surface water, and othermiscellaneous applications (such as landfill leachate processing).Influent concentrations of PFASs may vary by orders of magnitude overtime for specific media or applications, and these variable influentconcentrations, along with other general water quality parameters (e.g.,pH) may influence the performance and operating costs for each specifictreatment technology.

One technology commonly used for the removal of various PFASs from anaqueous stream is activated carbon adsorption. Activated carbontreatment or adsorption is used to adsorb natural organic compounds,taste and odor compounds, and synthetic organic chemicals indrinking-water supplies, for example. PFAS adsorption occurs at theinterface between the liquid and solid phase. Activated carbon is aneffective solid adsorbent, as it is a highly porous material andprovides a large surface area upon which contaminants may be adhered.Activated carbon usually is made from organic materials with high carboncontents such as wood, lignite, and coal, and often is used in agranular form called granular activated carbon (GAC), powdered activatedcarbon, or biochar.

A person having ordinary skill in the art understands that the cost ofactivated carbon treatment, including the cost of handling the spentactivated carbon waste, is high due to the high amounts of activatedcarbon needed for filtration and the high amounts of waste generatedfrom the spent carbon after exhaustion and disposal of the hazardouswaste. The footprint per flow of the average activated carbon treatmentfacility also is high due to the carbon filtration needing a contacttime of about five to seven minutes, which result in large size unit orvolume of vessels for required flow. For example, a 100 gallon perminute system needs about a 500 gallon to a 700 gallon filtration vesselcapacity.

Another technology commonly used for the removal of various PFASs froman aqueous stream is ion exchange or resin exchange. Ion exchange resinsare made up of highly porous, polymeric material(s) that is/are acid,base, or water insoluble. The tiny beads that make up the resin oftentimes are made up of hydrocarbons. There are two broad categories of ionexchange resins: cationic and anionic. The negatively charged cationicexchange resins (CER) are effective at removing positively-chargedcontaminants, and the positively charged anion exchange resins (AER) areeffective at removing negatively-charged contaminants, like PFASs. Ionexchange resins are characterized as tiny and powerful magnets thatattract and hold the target contaminant material from passing with theaqueous stream. In practice, the negatively charged PFAS ions areattracted to the positively charged anion resins. AER has shown to havea high capacity for many PFAS; however, it is typically more expensivethan GAC at an equally large footprint per flow. Once exhausted, the ionexchange beds typically are regenerated with caustic or alkaline liquidsolutions, which generate alkaline PFAS contaminated waste streams thatmust be processed at high risk and cost.

Another technology commonly used for the removal of various PFASs froman aqueous stream is membrane filtration. High-pressure membranes, suchas nanofiltration membranes or reverse osmosis membranes, for example,are effective at removing PFASs. Reverse osmosis membranes are moreselective than nanofiltration membranes; therefore, membrane filtrationtechnology depends on membrane permeability characteristics andselectivity. A standard difference between nanofiltration and reverseosmosis technology is that a nanofiltration membrane will rejecthardness to a high degree (i.e., will soften by removing polyvalentcations), but will pass sodium chloride, for example. A reverse osmosismembrane, on the other hand, will reject all salts to a high degree.Consequently, nanofiltration membranes may remove particles andparticulates while retaining minerals, which reverse osmosis membraneswould likely capture.

Research shows that high-pressure membranes typically are more thanabout 90% effective at removing a wide range of PFASs, includingshort-chain PFASs. Despite the high-pressure membrane's effectiveness atremoving PFASs, approximately 20% of the feedwater—the water coming intothe high-pressure membrane system—is retained as a concentrated wastethat must be handled, processed, and ultimately disposed of. A personhaving ordinary skill in the art understands that a concentrated wastestream at 20 percent of the feedwater is difficult and costly to handleespecially when the concentrated waste is loaded in PFASs. For example,the associated operating costs are an order of magnitude greater thanthat of GAC or ion exchange systems.

It is, therefore, desirable to overcome the deficiencies of, and providefor improvements to, the state of the prior art. Thus, there is a needin the art for a system and method for removing PFASs from acontaminated aqueous stream that provides a more efficient and effectivesystem for solving the problems in the art and improving the state ofthe art.

Accordingly, there is now provided within this disclosure a system andmethod of use for overcoming the aforementioned difficulties andlongstanding problems inherent in the art. A better understanding of theprinciples and details of the present invention will be evident from thefollowing detailed description.

BRIEF SUMMARY OF THE INVENTION

Exemplary embodiments are directed to a system for removing per- andpolyfluorinated alkyl substances from a contaminated aqueous stream. Inone exemplary embodiment, the system comprises an agitation andflocculation system and a particulate filter capture system.

Optionally, the system may comprise a feedback system configured toconsider the concentration of at least one of a group consisting ofperfluoroalkylcarboxylic acids, perfluoroalkyl sulfonates,perfluoroalkyl-sulfonic acids, and perfluorosulfonamidoacetic acids inthe aqueous stream, and the concentration of at least one of the groupconsisting of perfluoroalkylcarboxylic acids, perfluoroalkyl sulfonates,perfluoroalkyl-sulfonic acids, and perfluorosulfonamidoacetic acids inthe decontaminated aqueous stream exiting the system—to make efficientuse of the anhydrite quantity introduced into and used by the system. Asanother option, the system also may comprise a water softening systemfor softening the decontaminated aqueous stream exiting the system.

The agitation and flocculation system is configured to receive anaqueous stream contaminated with contaminants, and configured to receivean anhydrite quantity as a primary flocculant. In certain exemplaryembodiments, the anhydrite quantity comprises solid anhydrite particlesor granules—either pre-hydrated or dry or a combination thereof. Inother exemplary embodiments, the anhydrite quantity is introduced intothe aqueous stream via a liquid carrier.

The agitation and flocculation system comprises a means for agitatingthe aqueous stream and a means for mixing the aqueous stream with theanhydrite, such that effectively positively charged calcium ions hydratefrom the anhydrite and interact with the negatively charged contaminantsto form a precipitate of calcium sulfate hydrate+contaminant complexesin the aqueous stream. The agitation and flocculation system also isconfigured to cease agitating and mixing the aqueous stream such that aportion of the calcium sulfate hydrate+contaminant complexes settle orare redirected under the influence of gravity, and such that a portionof the calcium sulfate hydrate+contaminant complexes resist theinfluence of gravity and remain suspended in a partially decontaminatedaqueous stream. In certain exemplary embodiments, the agitation andflocculation system comprises at least one from a group consisting ofstirring blades, baffles, vortex generators, liquid flow devices, andgas or air pumps for bubbles or microbubble generation, to increase thekinetics between the aqueous stream and the anhydrite quantity.

In another exemplary embodiment, the system comprises a fixed-bed typecross-flow system and a particulate filter capture system. The fixed-bedtype cross-flow system may be configured as a fixed-bed type cross-flowfilter system comprising a cartridge-type filter media comprising theanhydrite quantity. The fixed-bed type cross-flow system also may beconfigured and structured to have the agitation and flocculation systemdownstream of the fixed-bed type cross-flow system and upstream of theparticulate filter capture system.

To go along with the illustrative and exemplary systems, exemplaryembodiments of the present invention are directed to a method ofremoving per- and polyfluorinated alkyl substances from a contaminatedaqueous stream. In one exemplary embodiment, the method comprises theacts of: providing an anhydrite quantity; contacting the anhydritequantity with an aqueous stream contaminated with contaminants;increasing the kinetics of the anhydrite quantity in contact with theaqueous stream such that effectively positively charged calcium ionshydrate from the anhydrite and interact with the negatively chargedcontaminants to form a precipitate of calcium sulfatehydrate+contaminant complexes in the aqueous stream; and collecting theprecipitate of calcium sulfate hydrate+contaminant complexes from theaqueous stream.

In certain exemplary embodiments, the collecting act comprises capturingthe calcium sulfate hydrate+contaminant complexes in the aqueous streamvia a particulate filter capture system comprising filter media.Further, the collecting act may comprise drying the captured calciumsulfate hydrate+contaminant complexes, or processing the dried capturedcalcium sulfate hydrate+contaminant complexes via techniques like, butnot limited to, milling, grinding, and pulverizing the dried capturedcalcium sulfate hydrate+contaminant complexes.

BRIEF DESCRIPTION OF THE DRAWINGS

In the figures, like reference numbers refer to like parts throughoutthe various views unless otherwise indicated. For reference numbers withletter character designations such as “102A” or “102B”, the lettercharacter designations may differentiate two like parts or elementspresent in the same figure. Letter character designations for referencenumbers may be omitted when it is intended that a reference numeral toencompass all parts having the same reference number in all figures.

FIG. 1 is a schematic diagram of a first exemplary embodiment of asystem for removing PFASs from a PFAS contaminated aqueous stream.

FIG. 2 is a schematic diagram of a second exemplary embodiment of asystem for removing PFASs from a PFAS contaminated aqueous stream.

FIG. 3 is a flow diagram showing the steps of an Illustrative embodimentof a method of removing PFASs from a PFAS contaminated aqueous stream.

DETAILED DESCRIPTION OF THE INVENTION

For a further understanding of the nature, function, and objects of thepresent invention, reference should now be made to the followingdetailed description taken in conjunction with the accompanyingdrawings. While detailed descriptions of the preferred embodiments areprovided herein, as well as the best mode of carrying out and employingthe present invention, it is to be understood that the present inventionmay be embodied in various forms. Therefore, specific details disclosedherein are not to be interpreted as limiting, but rather as a basis forthe claims and as a representative basis for teaching one skilled in theart to employ the present invention in virtually any appropriatelydetailed system, structure, or manner. The practice of the presentinvention is illustrated by the included Example, which is deemedillustrative of both the process taught by the present invention and ofthe results yielded in accordance with the present invention.

As used herein, the word “exemplary” or “illustrative” means “serving asan example, instance, or illustration.” Any implementation describedherein as “exemplary” or “illustrative” is not necessarily to beconstrued as preferred or advantageous over other implementations.

Embodiments and aspects of the present invention provide an efficient,effective, and economical filtration system for removing PFASs fromcontaminated aqueous streams. The inventive concepts described hereinalso provide a solution that is not susceptible to the limitations anddeficiencies of the prior art. The inventive concepts described hereinlessen the operating-costs, capital expenditures, and/or infrastructureassociated with the removal of PFASs from contaminated aqueous streams.

A first exemplary embodiment of the present invention provides a systemfor and a method of removing PFASs from PFAS contaminated aqueousstreams via chemical aided capture and filtration. The system and methodis configured to process PFAS contaminated aqueous streams without needfor activated carbon filters or equivalent. The system and method alsois configured to reduce operating costs, between about 30% to about 40%when compared to activated carbon filtration systems and ion exchangeresin systems, and between about 50% to about 70% when compared to otherprior art treatment processes such as reverse osmosis.

In particular, the system and method reduces the non-useful, orpotentially toxic, outputs from PFAS processing. The system and methodalso efficiently and effectively treats and decontaminates aqueousstreams, with limited bi-products and/or residues that cannot becaptured, filtered, and/or reused, recycled, or safely disposed of, andwith limited quantities of new or fresh waste materials or reagents.Further, the system and method also efficiently and effectively treatsand decontaminates the aqueous stream without need for any secondary pHadjustment pre-treatment steps.

Specifically, prior art carbon filtration, membrane filtration, or ionexchange methods are very susceptible to fluctuations in pH,temperature, salinity, and/or the presence of any other type of organicsin addition to PFAS/PFOS. The system and method of the presentdisclosure—unlike carbon filtration or membrane filtration or ionexchange—works on a wide range of pH values for the aqueous stream,between about 4 to about 11, and a wide range of temperatures frombetween about 32 degrees Fahrenheit (F) to about 90 degrees F., and widerange of salinity levels of up to about 32,000 parts per million (ppm),and are not affected by the presence of organics. Outside of theseranges, the system and method 100 may operate with known modificationsand/or pre-conditioning and/or post-conditioning steps for the stream.

A second exemplary embodiment of the present invention provides atransportable and/or stand-alone system, and associated method, that canbe deployed on an emergency or quick response basis to purify PFAScontaminated aqueous streams emitted from chemical processing and/ormanufacturing facilities, or emitted as chemical runoff and/or leachate.The system and method is configured to substantially purify, ornearly-completely purify, PFAS contaminated aqueous streams laden with,amongst others, PFOS, PFOA, and any combinations thereof. The PFAScontaminated aqueous stream may be laden with various PFAS-types ofmeasurable and unmeasurable quantities—due to the current state ofdeployable technology and/or the sometimes extreme dilution of thecontaminated stream—and other similarly structured and chargedcontaminants. Yet the system and method is proven to capture commonlymeasurable PFAS-types (perfluoroalkyl carboxylic acids, perfluoroalkylsulfonates, perfluoroalkyl sulfonic acids, andperfluorosulfonamidoacetic acids, for example) that directly facilitatecapture of the—usually unmeasurable—other PFAS-types commonly associatedwith the contaminated stream and other similarly structured and chargedcontaminants.

A third exemplary embodiment of the present invention provides atransportable, stand-alone system, and associated method, configured tobe mounted on a trailer or skids that can be deployed on an emergency orquick response basis, to purify PFAS contaminated fluid streams. Thesystem and method allows chemical processing and manufacturingfacilities, having internal cleanup issues, for example, to quicklypurify or nearly-completely purify FPAS contaminated aqueous streams.The system and method also allows municipalities, governments, andlocalities, as well as private consumers to purify or nearly-completelypurify PFAS contaminated aqueous streams. Once the issues in thefacility or locality are fixed, the system and method may be remobilizedand removed from the site in a short period of time. The system alsoeasily may be remobilized or ramped up within a short period of time, asneeded.

A fourth exemplary embodiment of the present invention provides achemical aided capture and filtration system and method—involving theuse of anhydrous calcium sulfate or anhydrite (Drierite©, for example)as a flocculant or precipitation and agglomeration agent—for the removalof PFASs from a PFAS contaminated aqueous stream. PFASs tend to havenegatively charged functional groups, while the anhydrite in the aqueousstream yields positively charged calcium ions. The anhydrite generallyexhibits limited solubility in water and exhibits retrograde solubility,i.e., the solubility decreases as temperature increase.

As such, the positively charged calcium ions from the hydrated anhydriteinteracts with at least some of the negatively charged groups PFASs—suchthat the buoyancy/weight of these PFASs in the aqueous stream isaffected—which causes the calcium sulfate hydrate+PFAS complexes toprecipitate. The insoluble calcium sulfate hydrate+PFAS complexes alsowill begin to agglomerate, which directly facilitates substantialcapture of the other PFASs in the contaminated stream that may be of atype that do not interact with the positively charged calcium ions butwould, nonetheless, still be bound-up by the calcium sulfatehydrate+PFAS complexes as they precipitate and/or agglomerate.

In this way, the system and method leverages flocculation,sedimentation, and/or filtration to purify the PFAS contaminated aqueousstream. In particular, the system and method may leverage flocculationand sedimentation—through gravity-induced settling of the calciumsulfate hydrate+PFAS insoluble precipitate complexes. In certainembodiments, the system and method then leverage filtration to filterout from the aqueous stream any un-sedimented or un-precipitatedagglomerated calcium sulfate hydrate+PFAS complexes along with theirbound-up or captured secondary PFASs—which secondarily flock onto theagglomerated calcium sulfate hydrate+PFAS complexes. As such, the systemand method is configured to process PFAS contaminated aqueous streamswithout need for activated carbon filters, ion exchange systems, reverseosmosis systems, membrane systems, or equivalent—although furtherprocessing of the aqueous stream would yield further purification anddecontamination without the limitations reported in the prior art.

Accordingly, further downstream processing under similar principles asexplained herein—using other hydrated forms of calcium sulfate likeCaSO₄.2 H₂O or gypsum and selenite (a mineral dihydrate of calciumsulfate), CaSO₄.½ H₂O or basanite (a hemihydrate, also known as plasterof Paris, either α-hemihydrate and β-hemihydrate of calcium sulfate),bauxite, alumina, and/or alum, etc.—would yield further purification anddecontamination without the limitations reported in the prior art.Further, the system and method result in a captured solid waste thatmore easily can be processed, transported, and disposed of than theactivated-chemical, liquid, or wet-waste of the prior art.

With the above context in mind, embodiments and aspects of the presentinvention become apparent from the drawings and the following detaileddescription.

FIG. 1 is a schematic diagram of a fifth exemplary embodiment of thepresent invention. FIG. 1 illustrates a generalized system-structure andmethod steps 100 for removing PFASs from a PFAS contaminated aqueousstream. The system 100 has as much as 95% lower waste generationside-effects when compared to an integrated activated carbon filter.

For example, in comparison to an activated carbon system used for PFASremoval, for 1 pound of PFAS compounds removed from the aqueous stream,the estimated cost of activated carbon is about $450 U.S. dollarsincluding cost of new activated carbon, replacement of spent carbon, andwaste disposal of the spent carbon. This generates about 101 pounds ofwaste to be disposed of. In stark contrast, the system 100, for the same1 pound of PFAS compounds removed from the aqueous stream, the estimatedcost is around $100 U.S. dollars including consumables and disposal.This is about 75% reduction in estimated operating costs. The system 100also generates less than about 7 pounds of waste, which is more thanabout 90% waste reduction. Further, the footprint of the system 100 isabout 50% smaller than activated the carbon system, to achieve the sameperformance.

For purposes of the system 100 and the associated method, the PFAScontaminated feedwater 6 is fed initially into a primary agitation andflocculation tank 1. The feedwater 6 is fed via a pump, by gravity flow,by any other equivalent, or by any other method known to a person havingordinary skill in the art. Although the primary agitation andflocculation tank 1 is shown as a single tank, it is envisioned that theagitation and flocculation may occur along a series of interconnectedand interrelated tanks, or any other system known to a person havingordinary skill in the art for inducing mixing, agitation, aggregation,precipitation, agglomeration as between the contaminated feedwater 6 andthe flocculant, and/or any other common additive, to be introduced intothe system 100.

In particular, the primary agitation and flocculation tank 1 isconfigured to receive the PFAS contaminated feedwater 6 and a quantityof anhydrite 7 as the primary flocculant. The quantity of anhydrite 7may be introduced into the feedwater 6 as solid particles or granules,either hydrated or dry, as a liquid mixture, or as a fixed bed ofmaterial within the tank(s) (see FIG. 2; system 200). The quantity ofanhydrite 7 also may be determined by a feedback system, which takesinto consideration the concentration of at least one of the measurablePFASs in the feedwater 6 (perfluoroalkyl carboxylic acids,perfluoroalkyl sulfonates, perfluoroalkyl sulfonic acids, and/orperfluorosulfonamido-acetic acids, for example) and the measurableconcentration of a least one of the measurable PFASs in the final outlettreated aqueous stream 10 of the system 100, to make most efficient useof the quantity of anhydrite 7 introduced into and used by the system100. The feedwater 6 may flow through, or function as the inlet feedliquid, for the quantity of anhydrite 7.

Further, the primary agitation and flocculation tank 1 is configured,and has the necessary structure(s), for mixing and agitating thefeedwater 6 with the added quantity of anhydrite 7 as flocculant. Thetank 1 may have stirring blades, baffles, or equivalent structures, mayrely on vortex generators or liquid flow devices to increase thekinetics between the PFAS contaminated feedwater 6 and the anhydrite 7mixture, or may rely on pumps introducing gas or air into the mixturewithin the tank 1. The tank 1, specifically, is configured to receivecompressed or uncompressed gas or air, and to form gas bubbles ormicrobubbles 8 in the feedwater 6 and the anhydrite 7 mixture.

With the feedwater 6 and the anhydrite 7 mixed and agitated in theprimary agitation and flocculation tank 1, the generally insolubleanhydrite begins to hydrate and release the positively charged calciumions in the PFAS contaminated feedwater 6. The negative charge of thePFASs interacts with the effectively positively charged and hydratedanhydrite to form calcium sulfate hydrate+PFAS complexes in thefeedwater 6 within the tank 1. As the insoluble calcium sulfatehydrate+PFAS complexes begin to agglomerate, they also begin toprecipitate. Together, this directly facilitates substantial capture ofthe other PFASs in the feedwater 6 that may be of a type that do not/arenot known to/have not been evidenced yet to interact with the positivelycharged calcium ions but would, nonetheless, still be bound-up by thecalcium sulfate hydrate+PFAS complexes as they precipitate and/oragglomerate.

Upon cessation of the mixing and agitation of the feedwater 6 and theanhydrite 7 mixture in the tank 1, the calcium sulfate hydrate+PFAScomplexes begin to settle under the influences of gravity, along withtheir bound-up or captured secondary PFASs (which secondarily flock ontothe agglomerated calcium sulfate hydrate+PFAS complexes, as explained indetail herein). The calcium sulfate hydrate+PFAS complex(es), having agreater weight and different structure than the component parts, beginto either precipitate or aggregate and form a solid deposit. As thebarriers to aggregation are reduced by the nature of calcium sulfatehydrate+PFAS complex, the calcium sulfate hydrate+PFAS complexes beginto agglomerate to form floc or flakes which further precipitate. Somecomplexes resist precipitation and remain suspended in the feedwater 6.Those calcium sulfate hydrate+PFAS complexes 9 that do precipitate arethen separated from the remainder of the liquid phase in the tank 1, forfurther processing and drying, and for collection and disposal. Thecalcium sulfate hydrate+PFAS complexes 9 are characterized as agenerally insoluble calcium salt.

Despite the chemical-aided capture of the majority of the PFASs in thefeedwater 6, the remainder of the liquid phase in the tank 1, aftercollection of the precipitant 9, likely contains trace amounts ofunprecipitated calcium sulfate hydrate+PFAS complexes. The residualcalcium sulfate hydrate+PFAS complexes, nonetheless, are larger in sizethan the component parts, which makes them easier to capture physicallyor mechanically, e.g., makes them easier to simply filter-capture in aparticulate filter without need for activated carbon filter systems oradsorbent beds, etc. The system 100 and the entire method from start tofinish including precipitation and physical/mechanical capture removesupwards of 99.9 percent of the PFASs in the liquid phase.

More specifically, the remainder of the liquid phase in the tank 1,after collection of the precipitate 9, and containing trace amounts ofunprecipitated calcium sulfate hydrate+PFAS complexes, is passed into 2a cross-flow filter system 3. The cross-flow filter system 3 of system100 comprises filter media 4 defining an interior 5. The filter media 4comprises hydrophobic materials, e.g., melt blown polypropylene, spiralwound cellulose, nylon, glass, and/or can be selectively electricallycharged, and may take various forms such as a cylindrical filtercartridge, for example. The flow rate of the filter media 4, in certainexemplary embodiments, may range from between about 0.25 liters perminute to about 20.0 liters per minute per 10 inch length and 2.5 inchdiameter of filter and contact time of less than about 1 minute. Insteadof a cross-flow filter system 3, a fixed bed of filter media also may beused; however, a cross-flow system with a radial flow design, forexample, ensures high surface area and hence high flow and a smallfootprint when compared to a fixed-bed filter configuration.

In exemplary embodiments with cartridge configurations, the dimensionsof each filter cartridge may be in the range of between about 5 inchesto about 60 inches in length and between about 2.5 inches to about 6inches in diameter. In exemplary embodiments with fixed-bed filterconfigurations, the flow rate may be in the range of between about 0.25liters per minute to about 4 liters per min per 2.5 inch diameter. Thesedimensions may be significantly scaled up or down depending on thespecific need, e.g., for industrial fixed installations. In otherexemplary embodiments, other types of particulate filter capture systemsare envisioned such as depth filters, multimedia filter systems, orsand-bed filters with flow from top to bottom or bottom to top. For adepth filter-like system, for example, the contact time may be betweenabout 1 second to about 1 minute.

Returning to system 100, as the remainder of the liquid phase in thetank 1 is passed over 2 the filter media 4, the filter media 4 cancapture all of the trace amounts of unprecipitated calcium sulfatehydrate+PFAS complex(es)—so long as the surface area and flow rates aremanaged—and the filter media 4 is maintained or replaced as needed. Asthe name implies, this is a cross-flow filter system wherein the liquidphase travels tangentially across the surface of the filter media 4,rather than into/through the filter media 4. The principal advantage ofthis arrangement is that filter cake—which can blind thefilter—substantially is washed away during the filtration process, whichincreases the length of time that the filter media 4 can be effectivelyused. In this way, system 100 can operate as a continuous process,unlike batch-wise dead-end filtration systems. The resulting outletliquid 10 coming out of the filter media 4 is the final treated aqueousstream, which has been substantially decontaminated of PFASs, and whichcan now exit the system 100.

As the aqueous stream has been hardened by the introduction of calciumions via the anhydrite treatment, it is envisioned that the system 100may additionally comprise a water softening subsystem for the finaloutlet treated aqueous stream 10. It also is envisioned that, oncedifferential pressure in the filter media 4 has reached a predeterminedstage, caused by the amount of unprecipitated calcium sulfatehydrate+PFAS complexes captured, the filter media 4 may be backwashed,reused, or disposed of. Other techniques that may be employed includealternating tangential flow, clean-in-place techniques, diafiltration,and/or process flow disruption.

FIG. 2 is a schematic diagram of a sixth exemplary embodiment of thepresent invention. FIG. 2 illustrates a generalized system-structure andmethod steps 200 for removing PFASs from a PFAS contaminated aqueousstream. Like system 100, the system 200 has as much as 95% lower wastegeneration side-effects when compared to an integrated activated carbonfilter.

For example, in comparison to an activated carbon system used for PFASremoval, for 1 pound of PFAS compounds removed from the aqueous stream,the estimated cost of activated carbon is about $450 U.S. dollarsincluding cost of new activated carbon, replacement of spent carbon, andwaste disposal of the spent carbon. This generates about 101 pounds ofwaste to be disposed of. In stark contrast, the system 100, for the same1 pound of PFAS compounds removed from the aqueous stream, the estimatedcost is around $100 U.S. dollars including consumables and disposal.This is about 75% reduction in estimated operating costs. The system 100also generates less than about 7 pounds of waste, which is more thanabout 90% waste reduction. Further, the footprint of the system 100 isabout 50% smaller than activated the carbon system, to achieve the sameperformance.

For purposes of the system 200 and the associated method, the PFAScontaminated feedwater 6 is processed via a fixed-bed type structure 11configured to hold the flocculant. Like the system 100 structure, thefeedwater 6 is fed via a pump, by gravity flow, by any other equivalent,or by any other method known to a person having ordinary skill in theart. The fixed-bed type structure 11 is configured as a cross-flowsystem but may be configured as a depth system or any other equivalent;however, regardless of the embodiment discussed, the anhydrite is heldas part of the media, multi-media, cassette, and/or cartridge, etc. Theanhydrite may be in the form of solid particles or granules, eitherhydrated or dry until the system is introduced to the feedwater 6.Flocculation begins to occur within the anhydrite media of the fixed-bedtype structure 11, and downstream therefrom, via the positively chargedcalcium ions hydrated from the anhydrite media.

In exemplary embodiments with a depth configuration for the fixed-bedtype structure 11, multiple porous layers of filter-like media are usedto make contact with the PFAS contaminated feedwater 6. Due to thetortuous and channel-like nature of the filtration media, the feedwater6 enters and interacts with the anhydrite within its structure, asopposed to substantially on or near the surface. A depth filterconfiguration provides the added advantage of attaining a highseparation efficiency, and having the ability to be used withsubstantially higher flow rates. A depth filter configuration maycomprise cassettes (pads or panels), cartridges, deep-beds such as sandfilters, and lenticulars.

Returning to system 200, although the fixed-bed type structure 11 isillustrated in FIG. 2 to comprise a single media or a single fixed bed,it is envisioned that the PFAS contaminated feedwater 6 may flow throughor along a series of interconnected and/or interrelated fixed-bed typestructure(s) 11, and/or a series of agitation and flocculation tanks 1like those of system 100. The system 200 also may comprise any othersystem known to a person having ordinary skill in the art for promotinginteraction between the PFASs and the positively charged calcium ionshydrated from the anhydrite, e.g., percolators, bubblers, agitators.

The fixed-bed type structure 11 of system 200 receives a quantity ofanhydrite and holds it as the primary flocculant. Like system 100, thequantity of anhydrite to be maintained or replenished in the fixed-bedtype structure 11 of system 200 may be determined by a feedback systemthat takes into consideration of a least one of the measurable PFASs inthe feedwater 6 (perfluoroalkylcarboxylic acids, perfluoroalkylsulfonates, perfluoroalkyl sulfonic acids, and/orperfluorosulfonamido-acetic acids, for example), the initial and currentquantity of anhydrite in the fixed-bed type structure 11, the measurableconcentration of a least one of the measurable PFASs in the final outlettreated aqueous stream 10, etc.—to make most efficient use of thequantity of anhydrite introduced into and used by the system 200.

Again, as the insoluble calcium sulfate hydrate+PFAS complexes begin toagglomerate, they also begin to precipitate. Together, this directlyfacilitates substantial capture of the other PFASs in the feedwater 6that may be of a type that do not/are not known to/have not beenevidenced yet to interact with the positively charged calcium ions butwould, nonetheless, still be bound-up by the calcium sulfatehydrate+PFAS complexes as they precipitate and/or agglomerate.

In the cross-flow configuration, the fixed-bed type structure 11includes a filter-type media 13 comprising anhydrite granules and/orpowder 15. In other exemplary embodiments, the filter-type media 13essentially comprises anhydrite granules and/or powder. The cross-flowsystem 11 may take various forms such as that of planar filter(s) for avessel or cylindrical filter cartridge(s) for a canister. In exemplaryembodiments with cartridge configurations, the dimensions of eachcartridge may be in the range of between about 5 inches to about 60inches in length and between about 2.5 inches to about 6 inches indiameter. These dimensions may be significantly scaled up or downdepending on the specific need, e.g., for industrial fixedinstallations.

Returning to the system 200, the contact time and the amount ofanhydrite granules and/or powder 15 in the filter-like media 13 isadjusted based on the expected or anticipated PFAS concentration in thefeedwater 6 and the flow rate of the feedwater 6—whether or not activelycontrolled. The contact time between the PFASs in the feedwater 6 andthe anhydrite granules and/or powder 15 is between about 1 second toabout 1 minute. With the feedwater 6 and the anhydrite granules and/orpowder 15 in contact within the fixed-bed type structure 11, thegenerally insoluble anhydrite begins to hydrate and release positivelycharged calcium ions into the feedwater 6. The negative charge of thePFASs interact with the effectively positively charged and hydratedanhydrite to form calcium sulfate hydrate+PFAS complexes in thefeedwater 6 within in the filter-like media 13 and downstream of thefilter-like media 13.

From within, and upon exiting the fixed-bed type structure 11—as thebarriers to aggregation are reduced by the nature of the calcium sulfatehydrate+PFAS complex—the calcium sulfate hydrate+PFAS complexes begin toagglomerate and to form floc; however, due to the force of the flowcoming out of the fixed-bed type structure 11, none of the agglomeratesor floc settle. Like system 100 of FIG. 1, the calcium sulfatehydrate+PFAS complexes are larger in size than the component parts,which makes them easier to capture physically or mechanically, e.g.,makes them easier to simply filter-capture in a particulate filterwithout need for activated carbon filter systems or adsorbent beds, etc.The system 200 and the entire method from start to finish includingprecipitation and physical/mechanical capture removes upwards of 99.9percent of the PFASs in the liquid phase.

Next, as flocculation begins to occur within the anhydrite fixedfilter-like media 13 of the fixed-bed type structure 11 and downstreamtherefrom, the calcium sulfate hydrate+PFAS complexes are separated fromthe liquid phase exiting the fixed-bed type structure 11. Specifically,the liquid phase is passed over 2 an actually cross-flow filter 17differently configured from the fixed-bed type cross-flow system 11. Thecross-flow filter 17 is substantially identical to the cross-flow filterexcept for the difference described herein. Instead of a cross-flowfilter system 17, a fixed bed of filter media also may be used; however,a cross-flow system with a radial flow design, for example, ensures highsurface area and hence high flow and a small footprint when compared toa fixed-bed filter configuration.

Regardless of the specific configuration used, the cross-flow filter 17can capture all of the unprecipitated calcium sulfate hydrate+PFAScomplexes—so long as the filter media 19 cartridge, multimedia, sandbed, etc. and flow 2 are managed—and the encapsulating calcium sulfatehydrate+PFAS complexes 21 are removed, managed, and/or processed asneeded. This may require removal and replacement of the filter media 19and/or removal and processing of the encapsulating calcium sulfatehydrate+PFAS complexes 21. The flow rate of the filter media 4, incertain exemplary embodiments, may range from between about 0.25 litersper minute to about 20.0 liters per minute per 10 inch length and 2.5inch diameter of filter and contact time of less than about 1 minute.

In exemplary embodiments with cartridge configurations, the dimensionsof each filter cartridge may be in the range of between about 5 inchesto about 60 inches in length and between about 2.5 inches to about 6inches in diameter. In exemplary embodiments with simplified fixed-bedfilter configurations, the flow rate may be in the range of betweenabout 0.25 liters per minute to about 4 liters per min per 2.5 inchdiameter. These dimensions may be significantly scaled up or downdepending on the specific need, e.g., for industrial fixedinstallations. In one exemplary embodiment, other types of particulatefilter capture systems are envisioned such as depth filters, multimediafilter systems, or sand-bed filters with flow from top to bottom orbottom to top. In another embodiment, the filter(s) may be installed asa single or multiround configuration holding multiple filters in onevessel depending on the flow capacity and pressure drop requirements.

In this way, the resulting outlet liquid stream 23 coming out of thefilter media 19 of the cross-flow filter 17 is the final treated aqueousstream, which has been substantially decontaminated of PFASs, and whichcan now exit the system 200. As the aqueous stream has been hardened bythe introduction of anhydrite, it is envisioned that the system 200 mayadditionally comprise a water softening subsystem for the final outletliquid stream 23. It also is envisioned that, once differential pressurein the filter media 19 has reached a predetermined stage, caused by theamount of unprecipitated calcium sulfate hydrate+PFAS complexescaptured, the filter media 19 may be backwashed, reused, or disposed of.Other techniques that may be employed include alternating tangentialflow, clean-in-place techniques, diafiltration, and/or process flowdisruption.

Example

The following is a non-limiting illustrative example of the presentinvention when applied under experimental conditions, for a PFAScontaminated aqueous stream, and the experimental results thereof, basedon the system and method of FIG.

The system used has an about 1 liter per minute feedwater intakecontaining about 1 ppm of PFASs (each; see Table 1). The primaryagitation and flocculation tank has a capacity of about 10 liters. Aquantity of anhydrite granules of about 2.0 milligrams (mg) isintroduced into the feedwater. The feedwater functions as the inlet feedliquid for the 2.0 mg of anhydrite. The ratio of flocculant to expectedquantity of PFASs in the tank ranges between about 0.3 to about 1000.

The primary agitation and flocculation tank mixes and agitates thefeedwater with the anhydrite as flocculant. The tank forms gas bubblesor microbubbles in the feedwater and the anhydrite mixture. With thefeedwater and the anhydrite mixed and agitated in the tank, thegenerally insoluble anhydrite begins to hydrate and interact with thePFASs to form calcium sulfate hydrate+PFAS complexes in the feedwaterwithin the tank.

Upon cessation of the mixing and agitation of the feedwater and theanhydrite mixture in the tank, the calcium sulfate hydrate+PFAScomplexes begin to either precipitate or aggregate. Some complexesresist precipitation and remain suspended in the feedwater. The tank hasa residence time of about 5 minutes or greater to yield the majority ofthe precipitate product, which contains from between about 95% to about99.9% of the PFASs that are in feedwater intake.

The precipitate is then separated from the remainder of the liquid phasein the tank, for further processing and drying, and for collection andweighing. The remainder of the liquid phase in the tank, aftercollection of the precipitate, contains the remaining about 0.05 mg toabout 0.0001 mg of trace unprecipitated calcium sulfate hydrate+PFAScomplexes.

Specifically, the liquid phase is passed into a cross-flow filter systemcomprising cylindrical filter media cartridge defining an interioroutlet. As the remainder of the liquid phase in the tank is passed overthe filter media, the filter media captures all or nearly all of theabout 0.05 mg to about 0.0001 mg trace unprecipitated calcium sulfatehydrate+PFAS complexes. The resulting outlet liquid coming out of thefilter media interior is substantially decontaminated of PFASs.

This is confirmed by the following experimental results presented asTable 1

TABLE 1 PFAS Chemical Removal Testing of Contaminated Aqueous Stream inparts per billion (ppb) (1 ppm = 1000 ppb) Inlet Outlet tank 1 Outletfilter PFOS/PFAS chemicals in water (6) (6) ppb (2) ppb (10) ppbPerfluorobutanesulfonic acid 1000 0.048 0.044 Perfluorobutanoic acid1000 0.041 0.046 Perfluorodecanesulfonate 1000 0.046 NDPerfluorodecanoic acid 1000 0.044  0.0017 Perfluorododecanoic acid 10000.053 ND Perfluoroheptanesulfonate 1000 0.048  0.0044 Perfluoroheptanoicacid 1000 0.042 0.023 Perfluorohexanesulfonic acid 1000 0.051 0.015Perfluorohexanoic acid 1000 0.054 0.044 Perfluorononanesulfonate 10000.039 ND Perfluorononanoic acid 1000 0.054  0.0046Perfluorooctanesulfonic acid 1000 0.044  0.0027 Perfluorooctanoic acid1000 0.055  0.0099 Perfluorooctansulfonamide 1000 ND NDPerfluoropentanesulfonate 1000 0.046 0.035 Perfluoropentanoic acid 10000.052 0.048 Perfluorotetradecanoic acid 1000 0.046 NDPerfluorotridecanoic acid 1000 0.045 ND Perfluoroundecanoic acid 10000.049 NDThe information in Table 1 illustrates (1) the feedwater concentrationsof PFASs, in ppb, (2) the liquid phase in the tank, after collection ofthe precipitate, concentrations of PFASs, in ppb, and (3) the resultingoutlet liquid coming out of the filter media concentrations of PFASs. NDindicates that the levels were not detectable by the current state ofdeployable technology and due to the extreme dilution of anything thatmight remain. Perfluorobutanesulfonic acid, Perfluorohexanesulfonicacid, and Perfluorooctanesulfonic acid are Perfluoroalkyl sulfonic acid.Perfluorodecane-sulfonate, Perfluoroheptanesulfonate,Perfluorononanesulfonate, and Perfluoro-pentane sulfonate arePerfluoroalkyl sulfonates. N-ethyl perfluorooctanesulfon-amidoaceticacid is a Perfluorosulfonamidocarboxylicacids/Perfluorosulfonamido-carboxylates. Perfluoro butanoic acid,Perfluoro decanoic acid, Perfluoro dodecanoic acid, Perfluoro heptanoicacid, Perfluorohexanoic acid, Perfluorononanoic acid, Perfluorooctanoicacid, Perfluoropentanoic acid, Perfluorotetradecanoic acid, Perfluorotridecanoic acid, and Perfluoro undecanoic acid arePerfluoroalkylcarboxylic acid/Perfluoroalkyl carboxylates.

Turning now to FIG. 3, FIG. 3 is a flow diagram of an illustrativemethod 1000 according to an exemplary embodiment. The method 1000discloses steps, not all of which are necessarily employed in each andevery situation, but which may have similarities to other exemplaryembodiments provided herein. The steps in the method 1000 may beperformed in or out of the order shown. The method 1000 comprises thesteps of: (1) providing an anhydrite quantity (1002); (2) contacting theanhydrite quantity with an aqueous stream contaminated with contaminants(1004); (3) increasing the kinetics of the anhydrite quantity in contactwith the aqueous stream such that effectively positively charged calciumions hydrate from the anhydrite and interact with the negatively chargedcontaminants to form a precipitate of calcium sulfatehydrate+contaminant complexes in the aqueous stream (1006); and (4)capturing the calcium sulfate hydrate+contaminant complexes in theaqueous stream via a particulate filter capture system comprising filtermedia (1008).

In some exemplary embodiments, the 1008 step may alternatively consistof collecting the precipitate of calcium sulfate hydrate+contaminantcomplexes in the aqueous stream that has settled out of solution orsuspension. The collected product may take the form of a hardcement-like product when taken out of aqueous stream and dried. Thecollected product encapsulates the PFAS contaminants and exhibitsinsignificant leaching of the contaminant back into the environment whenleft exposed to nature.

The various embodiments are provided by way of example and are notintended to limit the scope of the disclosure. The described embodimentscomprise different features, not all of which are required in allembodiments of the disclosure. Some embodiments of the presentdisclosure utilize only some of the features or possible combinations ofthe features. Variations of embodiments of the present disclosure thatare described, and embodiments of the present disclosure comprisingdifferent combinations of features as noted in the describedembodiments, will occur to persons with ordinary skill in the art. Itwill be appreciated by persons with ordinary skill in the art that thepresent disclosure is not limited by what has been particularly shownand described herein above.

What is claimed is:
 1. A system for removal of contaminants from acontaminated aqueous stream, the system comprising: a) an agitation andflocculation system configured to receive an aqueous stream contaminatedwith contaminants, and configured to receive an anhydrite quantity as aprimary flocculant, the agitation and flocculation system comprising ameans for agitating the aqueous stream and mixing the aqueous streamwith the anhydrite such that effectively positively charged calcium ionshydrate from the anhydrite and interact with the negatively chargedcontaminants to form a precipitate of calcium sulfatehydrate+contaminant complexes in the aqueous stream, the agitation andflocculation system also configured to cease agitating and mixing theaqueous stream such that a portion of the calcium sulfatehydrate+contaminant complexes settle or are redirected under theinfluence of gravity, and such that a portion of the calcium sulfatehydrate+contaminant complexes resist the influence of gravity and remainsuspended in a partially decontaminated aqueous stream; and b) aparticulate filter capture system comprising filter media, andconfigured to receive the partially decontaminated aqueous stream and tocapture the calcium sulfate hydrate+contaminant complexes that resistthe influence of gravity and remain suspended in the partiallydecontaminated aqueous stream, wherein the partially decontaminatedaqueous stream is flowed through the filter media to capture theremaining calcium sulfate hydrate+contaminant complexes to yield adecontaminated aqueous stream.
 2. The system for removal of contaminantsof claim 1, wherein the anhydrite quantity comprises solid anhydriteparticles or granules, either pre-hydrated or dry, or a combinationthereof.
 3. The system for removal of contaminants of claim 1, whereinthe anhydrite quantity is introduced into the aqueous stream via aliquid carrier.
 4. The system for removal of contaminants of claim 1,additionally comprising a feedback system configured to consider theconcentration of at least one of a group consisting ofperfluoroalkylcarboxylic acids, perfluoroalkyl sulfonates,perfluoroalkyl-sulfonic acids, and perfluorosulfonamidoacetic acids inthe aqueous stream, and the concentration of at least one of the groupconsisting of perfluoroalkylcarboxylic acids, perfluoroalkyl sulfonates,perfluoroalkyl-sulfonic acids, and perfluorosulfonamidoacetic acids inthe decontaminated aqueous stream, to make efficient use of theanhydrite quantity introduced into and used by the system.
 5. The systemfor removal of contaminants of claim 1, wherein the agitation andflocculation system comprises at least one from a group consisting ofstirring blades, baffles, vortex generators, liquid flow devices, andgas or air pumps for bubbles or microbubble generation, to increase thekinetics between the aqueous stream and the anhydrite quantity.
 6. Thesystem for removal of contaminants of claim 1, additionally comprising awater softening system for softening the decontaminated aqueous stream.7. A system for removal of contaminants from a contaminated aqueousstream, the system comprising: a) a fixed-bed type cross-flow systemconfigured to receive an aqueous stream contaminated with contaminants,and configured to hold an anhydrite quantity as a primary flocculant,the fixed-bed type cross-flow system configured to bring into contactthe aqueous contaminated stream with the anhydrite such that effectivelypositively charged calcium ions hydrate from the anhydrite and interactwith the negatively charged contaminants to form a precipitate ofcalcium sulfate hydrate+contaminant complexes in the aqueous stream, thefixed-bed type cross-flow system also configured to discharge theaqueous contaminated stream with sufficient flow to carry the calciumsulfate hydrate+contaminant complexes and aqueous stream downstreamwithout substantial precipitation or settling; and b) a particulatefilter capture system comprising filter media, and configured to receivethe aqueous contaminated stream and to capture the calcium sulfatehydrate+contaminant complexes suspended in the aqueous stream, whereinthe aqueous contaminated stream is flowed through the filter media tocapture the calcium sulfate hydrate+contaminant complexes to yield adecontaminated aqueous stream.
 8. The system for removal of contaminantsof claim 7, wherein the anhydrite quantity comprises solid anhydriteparticles or granules, either pre-hydrated or dry, or a combinationthereof.
 9. The system for removal of contaminants of claim 7,additionally comprising a feedback system configured to consider theconcentration of at least one of a group consisting ofperfluoroalkylcarboxylic acids, perfluoroalkyl sulfonates,perfluoroalkyl-sulfonic acids, and perfluorosulfonamidoacetic acids inthe aqueous stream, and the concentration of at least one of the groupconsisting of perfluoroalkylcarboxylic acids, perfluoroalkyl sulfonates,perfluoroalkyl-sulfonic acids, and perfluorosulfonamidoacetic acids inthe decontaminated aqueous stream, to make efficient use of theanhydrite quantity introduced into and used by the system.
 10. Thesystem for removal of contaminants of claim 7, wherein the fixed-bedtype cross-flow filter system comprises a cartridge-type filter mediacomprising the anhydrite quantity.
 11. The system for removal ofcontaminants of claim 7, additionally comprising a water softeningsystem for softening the decontaminated aqueous stream.
 12. The systemfor removal of contaminants of claim 7, additionally comprising anagitation and flocculation system downstream of the fixed-bed typecross-flow system and upstream of the particulate filter capture system.13. The system for removal of contaminants of claim 12, wherein theagitation and flocculation system comprises at least one from a groupconsisting of stirring blades, baffles, vortex generators, liquid flowdevices, and gas or air pumps for bubbles or microbubble generation, toincrease the kinetics between the aqueous stream and the anhydritequantity.
 14. A method of removing contaminants from a contaminatedaqueous stream, the system comprising: a) providing an anhydritequantity; b) contacting the anhydrite quantity with an aqueous streamcontaminated with contaminants; c) increasing the kinetics of theanhydrite quantity in contact with the aqueous stream such thateffectively positively charged calcium ions hydrate from the anhydriteand interact with the negatively charged contaminants to form aprecipitate of calcium sulfate hydrate+contaminant complexes in theaqueous stream; and d) collecting the precipitate of calcium sulfatehydrate+contaminant complexes from the aqueous stream.
 15. The method ofremoving contaminants from a contaminated aqueous stream of claim 14,wherein the collecting step comprises capturing the calcium sulfatehydrate+contaminant complexes in the aqueous stream via a particulatefilter capture system comprising filter media.
 16. The method ofremoving contaminants from a contaminated aqueous stream of claim 15,wherein the collecting step comprises drying the captured calciumsulfate hydrate+contaminant complexes.
 17. The method of removingcontaminants from a contaminated aqueous stream of claim 16, wherein thecollecting step comprises processing the dried captured calcium sulfatehydrate+contaminant complexes.
 18. The method of removing contaminantsfrom a contaminated aqueous stream of claim 17, wherein the processingthe dried captured calcium sulfate hydrate+contaminant complexes stepcomprises at least one from a group consisting of milling, grinding, andpulverizing the dried captured calcium sulfate hydrate+contaminantcomplexes.